Defect observation method and device and defect detection device

Abstract

A defect observation method for observing a defect on a sample detected by another inspection device with a scanning electron microscope including the steps of: optically detecting the defect using the position information for the defect: illuminating the sample including the defect with an illumination intensity pattern having periodic intensity variation in two dimensions by irradiating a plurality of illumination light beams onto the surface of the sample while phase modulating the light beams in a single direction and successively moving the light beams in small movements in a direction different from the single direction, imaging the surface of the sample that is illuminated by the illumination intensity pattern having periodic intensity variation in two dimensions and includes the defect detected by the other inspection device, and detecting the defect detected by the other inspection device from the image obtained through the imaging of the surface of the sample.

The invention claimed is: 
     
       1. A defect observation method comprising:
 obtaining, from a storage device, position information of a defect on a sample; 
 optically detecting the defect on a sample using a detector of a defect observation device using said position information of the defect on the sample;
 correcting the position information of the detected defect; and 
 
 observing the defect by a scanning electron microscope using the corrected position information, upon optical detection of the defect using the position information of the defect on the sample; 
 irradiating a same region on the sample having the defect with dark-field illumination lights from three directions, respectively, for interference with one another to generate an interference pattern having periodic intensity variation; 
 executing phase modulation of the interference pattern by slightly shifting an optical path length of the dark-field illumination system; 
 sample scanning by slightly shifting a stage on which the sample is placed, and irradiating the sample surface for illumination of the sample with an illumination intensity pattern having periodic intensity variation in a two-dimensional direction for shifting an imaging position on the detector; and 
 executing a super resolution process by selecting a signal used for the super resolution process from a shift amount derived from the sample scanning. 
 
     
     
       2. The defect observation method according to  claim 1 , wherein illumination of the sample with the illumination intensity pattern having periodic intensity variation in the two-dimensional direction includes steps of forming the illumination intensity pattern having periodic intensity distribution variation on the sample, and slightly shifting the sample sequentially in a direction different from the phase modulation direction while phase modulating the illumination intensity pattern. 
     
     
       3. The defect observation method according to  claim 1 , wherein illumination of the sample with the illumination intensity pattern having the periodic intensity variation in the two-dimensional direction is implemented by:
 irradiating the defect with lights each having a same wavelength from different directions using said position information of the to generate an interference pattern on the sample surface having the defect; 
 periodically shifting the interference pattern generated on the sample surface in one-dimensional direction by periodically changing a relative phase of lights each with the same wavelength irradiated from the different directions; and 
 in a state where the interference pattern is periodically shifted in one-dimensional direction, slightly shifting the sample sequentially in one-dimensional direction different from the one-dimensional direction. 
 
     
     
       4. The defect observation method according to  claim 1 , wherein illumination with the illumination intensity pattern having periodic intensity variation in the two-dimensional direction is implemented by alternately repeating irradiation of the sample surface with illumination lights having phase modulated on the sample surface having the defect in one-direction, and irradiation of the sample surface with the illumination lights slightly shifted sequentially in a direction different from the one-direction. 
     
     
       5. A defect observation device comprising:
 a stage on which a sample is placed; 
 an optical microscope configured to allow a detector of the defect observation device to optically detect a defect of the sample placed on the stage using position information of the defect; 
 a control system configured to correct the position information of the defect detected by the detector of the optical microscope; and 
 a scanning electron microscope which allows a scanning electron microscope to observe the defect using the corrected defect position information, wherein the optical microscope includes 
 an illumination light source, lens, and mirror which irradiate a same region on the sample having the defect with dark-field illumination lights from three directions for interference with one another to generate an interference pattern having periodic intensity variation; 
 a piezo element configured to perform phase modulation of the interference pattern generated by the illumination light source by slightly shifting optical path lengths of the dark-field illumination lights; and 
 a stage drive which slightly shifts the stage on which the sample is placed, 
 wherein the control system is further configured to slightly shift the stage on which the sample is placed by the stage drive while illuminating the sample with the illumination intensity pattern having periodic intensity variation in a two-dimensional direction, formed by the piezo element phase modulation of the interference pattern generated by the illumination light source, and to select a signal for a super resolution process from a shift amount derived from sample scanning of the illumination intensity pattern so as to execute the super resolution process using the selected signal. 
 
     
     
       6. The defect observation device according to  claim 5 , wherein:
 the illumination light source, lens, and mirror are configured to execute phase modulation of the plurality of illumination lights in one direction by forming the illumination intensity pattern having periodic intensity distribution variation on the sample; and 
 the piezo element configured to perform phase modulation spatially modulates the plurality of illumination lights by slightly shifting the sample sequentially in a direction different from the phase modulating direction. 
 
     
     
       7. The defect observation device according to  claim 6 , further comprising a plurality of mirrors configured to relatively change optical path lengths of the plurality of illumination lights. 
     
     
       8. The defect observation device according to  claim 5 , wherein the sample is illuminated with the illumination intensity pattern having periodic intensity variation in the two-dimensional direction by alternately repeating irradiation of the sample surface with illumination lights having phase modulated in the one direction on the sample surface having the defect by the illumination light source, and irradiation of the sample surface with the illumination lights slightly shifted in a direction different from the one direction by the piezo element configured to perform phase modulation.